Platelet activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) [1–3], a potent phospholipid mediator with a wide variety of biological activities, is involved in a number of proinflammatory/inflammatory manifestations, such as glomerulonephritis, glomerulosclerosis, atherosclerosis, cancer, allergy, and diabetes. The gene discussed is PCLAF; the disease is allergic disease.